When switching the interface language on any topic while logged in as admin, a permanent error message appears: “Failed to preview theme because it doesn’t exist, or you don’t have permission to access it.” Regular users do not experience this issue. Steps to reproduce: Log in as admin Open a…

Issue resolved! It was caused by a stale ?preview_theme_id=6 parameter in the Chrome browser URL. Once removed, the error disappeared. Thank you for pointing that out!

Do you get this issue on a different browser with the same admin user?

No. Only Chrome. And this problem only appeared today. I just checked and other browsers don’t have this problem.

Do you see a ?preview_theme_id=ID in the browser’s address bar at any point? This error message is only shown if you’re previewing a theme with an incorrect ID. You likely did this at some point on this browser and that value “stuck” in the Chrome tab/window.

Errore durante il cambio di lingua: il messaggio "topic doesn't exist" appare su tutti i topic

Supporto

Denis_Kovalenko (Don't worry - Be happy) 16 Aprile 2026, 2:58pm 5

Problema risolto! Era causato da un parametro obsoleto ?preview_theme_id=6 nell’URL del browser Chrome. Una volta rimosso, l’errore è scomparso. Grazie per averlo segnalato!

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Errore durante il cambio di lingua: il messaggio "topic doesn't exist" appare su tutti i topic

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